book-id-type Type of Book Identifier

Type of book identifier or the organization or system that defined the identifier.
OPTIONAL on element: <book-id>
Value Meaning
Text, numbers, or special characters The type of identifier “doi” or name or type of organization that created the identifier “publisher-id”.
Restriction @book-id-type is an optional attribute; there is no default.
Tagged Sample

A DOI as an identifier

 <book-id book-id-type="doi">10.1099/0193281217.001.0002</book-id>